To facilitate the transfer of advances in developmental biology to contemporary Newborn Medicine, the Harvard Medical School Program in Neonatal-Perinatal Medicine has established a 5-year training program to provide postresident fellows in neonatology with the opportunity to develop as independent and productive physician-scientists and to provide postdoctoral Ph.D. fellows with an introduction to developmental biology as applied to newborn and developmental diseases. The essential elements of this program have existed for 30 years and have proven successful in both the recruitment and training of highly committed postresident and postdoctoral trainees. To stimulate interest in academic neonatology at an earlier stage of career development, we are also requesting support for four short-term predoctoral students. These medical students participate in an ongoing (14-year old), laboratory-based summer research program that pairs them with postresident fellows. For postresident fellows, the 5-year training period is split into two phases. In the initial 3-year phase, fellows begin clinical training in the four Harvard Medical Area neonatal intensive care units and initiate Ph.D.- equivalent research training in a Boston-area laboratory. In the subsequent 2-year phase, mentored research training continues and the transition towards independence and faculty experience begins. For postdoctoral fellows, biomedical research training lasts for 3 years. This grant requests up to 3 years of support for each postresident trainee (to begin following the first year of clinical training) and up to three years of support for each postdoctoral trainee. Each year, 11 trainees will be supported, 75% postresidency, 25% postdoctoral, the same number supported by the current grant. The training is designed to produce productive independent investigators who are able to compete successfully for research funds. The trainees will utilize the best research mentors available in the Boston area, regardless of their institutional or departmental affiliation. The program promotes the achievement of explicit training goals, using a structured set of expectations as well as formal advising and evaluation procedures. The training program is designed to attract and nurture a "critical mass" of physician-scientist and basic-scientist trainees who are committed to applying developmental biology, molecular biology, genomics, cell biology, structural biology, gene therapy, biochemistry, informatics, biophysics and immunology in order to understand and treat newborn diseases and improve long-term developmental outcomes.